The lens is a basic optical device as seen everywhere in the optical apparatus. With the development of optical technology, the requirements for the lens are getting higher and higher. For example, the topography of the lens has become from a spherical surface into an aspherical surface of which in particular, the cylinder surface and the parabolic surface are most widely used. Moreover, there are also requirements on size and weight of the lens. For example, a Fresnel lens has advantages of small size, light weight and being easy to be reproduced and is widely used. However, the disadvantage of the existing lenses is that the functions are simple, the diffraction effect and the focal length are fixed, and cannot be flexibly changed according to the needs.